含双空孔缺陷试件三点弯曲冲击试验

Three Point Bending Impact Test of Specimen with Double-hole Defects

为了研究双孔缺陷对运动裂纹的作用机制,采用数字激光动态焦散线系统对含双空孔缺陷的有机玻璃板三点弯曲梁进行冲击断裂实验,分析研究了双空孔缺陷下裂纹扩展的路径、尖端动态强度因子、扩展速度以及焦散斑的变化规律。结果表明:空孔缺陷会吸引周围运动的裂纹,导致裂纹运动轨迹发生变化;含双空孔缺陷试件起裂难度显著增加,起裂的临界应力强度因子增加了24.29%;运动裂纹在接近双空孔缺陷时,双空孔缺陷对裂纹的扩展有明显的抑制作用,裂纹通过双空孔缺陷中心后,双空孔缺陷对裂纹的扩展有促进作用。

In order to study the action mechanism of double-hole defects on moving cracks,a digital laser dynamic caustics system was used to test the impact fracture of a three-point flexural beam of a plexiglass plate with double-hole defects.The crack propagation path,tip dynamic strength factor,propagation velocity and the change law of caustic speckle under double-hole defects were analyzed and studied.The results show that the cracks moving around are attracted by the empty hole defects,and the trajectory of the cracks is changed.The crack initiation difficulty of specimens with double-cavity defects increases significantly,and the critical stress intensity factor of crack initiation increases by 24.29%.When the moving crack is close to the double-empty hole defect,the double-empty hole defect has an obvious inhibition effect on the crack growth,and when the crack passes through the double-empty hole defect center,the double-empty hole defect has a promotion effect on the crack growth.